Hey Folks, Im wondering if this setup ;
can be tweaked to drive an IR Laser Diode instead of a plain old IR LED. I'm building a system where Im using this beam trigger outdoors, and I need better range than a simple diode. Ive procured a 3.5 - 5V 100ma laser diode and it works great in a continuous beam setup, but there is toooo much ambient IR in the summer for this type of arrangement. If I simply swap the laser for the LED, there isnt enough voltage (around 1.8v I think) to drive the laser...Thoughts?
If I simply swap the laser for the LED, there isnt enough voltage (around 1.8v I think) to drive the laser...Thoughts?
Did you connect the laser directly to an Arduino pin?
The usual answer is to put your detector in a tube (pointing directly at your IR source), to prevent ambient IR 'noise' affecting your set-up. Most model shops stock small diameter brass tubing, which is ideal for this.
Yes, to Pin3 (via a bread board, but yes) as described. I want the strongest output I can get so I skipped the resistor to get the full 5V ( it calls for a 1ohm, and in truth I don't have any).
Henry, I tried that, but in broad daylight in a wooded area, there is a FLOOD of IR light (green leave have a huge IR reflectance). I had to actually put my thumb over the tube to get the circuit to trip.
Yes, to Pin3 (via a bread board, but yes)
Continue to do that and you will destroy the pin 3 output driver. Continue to do that and you will very likely damage more than pin 3. There is a slight possibility that you have already caused permanent damage.
Keep the current less than 40mA per pin; 20mA is a good target.
There is no description of your circuit, no schematic, and the link is to Ken Shirriff's blog. I assume your claim of "as described" is a simple oversight rather than an attempt to be argumentative.
No no no, I wasnt being snippy, Shirriffs circuit (and most PWM circuits Ive found ) state that pin 3 and 11 are the timer pins. I stand warned though, I did not know that was the current limit on the pins. The pin still works fine, because Ive rebuilt Shirriffs circuit several times, and the one he describes with the IR led works just fine still.
You will have to add a driver for the laser. The voltage range (3.5 - 5V) is a problem. If possible try to pin that down to something more precise.
If the voltage is on the 3.5 side then a simple transistor (plus resistors) will work nicely. This forum (and the internet at large) is rife with laser diode examples.
If the voltage is on the 5 side then I have no idea what you should do.
Ok thats good info, I really appreciate that input,.